GB2510095A

GB2510095A - Separating oily materials from particulate materials

Info

Publication number: GB2510095A
Application number: GB1219565.7A
Authority: GB
Inventors: Michael Harris
Original assignee: EQUINOX ENVIRONMENTAL Ltd
Current assignee: EQUINOX ENVIRONMENTAL Ltd
Priority date: 2012-10-31
Filing date: 2012-10-31
Publication date: 2014-07-30
Also published as: GB201219565D0

Abstract

An apparatus for treating contaminated particulate mineral material, wherein the material is treated as an aqueous slurry, comprises a mixing chamber, slurry inlet 20, outlet 21, means for subjecting the slurry to extreme shear forces by injecting water from a first injection point 27 at extremely high pressure, wherein the slurry flows 33 from inlet to outlet, the cross-section of the mixing chamber increases adjacent the first injection point and the apparatus also includes a second water injection 34 means in the area of increased cross sectional area which creates a counter current to protect the mixing chamber walls from wear. The first injection point includes a ring of nozzles (see fig 4) and the second water injection means comprises a pair of nozzles. The apparatus forms part of a system (fig 1) which is used to treated oil contaminated sand or slit, comprising a high pressure reactor and desilter.

Description

SEPARATING OILY MATERIALS FROM PARTICULATE MATERIALS

Apparatus for separating oily material from particulate matter.

This invention relates to apparatus and methods for separating oily material from particulate matter, though it can be used in other situations for removing contamination from particulate material.

There are a variety of situations in which it is desired to separate oily material from particulate matter. One such scenario is the recovery of bitumen oil from tar sands. Tar sands are naturally occurring deposits of tarry or bituminous material mixed with particulate solid mineral material. Although a substantial proportion of bituminous material can be extracted by conventional processes, that processing gives rise to a substantial quantity of mineral material the particles of which are coated with tarry or bituminous material.

Downstream of the recovery of tarry and bituminous material and oils form natural deposits, the processing often gives rise to contaminated mineral materials for example which build up in the bottom of the treatment tanks or storage tanks. Particularly in the case of storage tanks, loss of oily materials in oily sludge, mud or the like, constitutes a substantial potential revenue loss.

Numerous suggestions have been made to process such materials with a view to separating the oily component from the mineral component.

It is well known that one way of separating oily material from particulate solid material onto the surface which it may be absorbed or adsorbed is to subject the material to extremely high shear forces in an aqueous medium.

US2008/0277318A describes a process for separating bitumen oil from tar sands in which an aqueous slurry is fed to a jet pump mixing chamber where it is subjected to very high mixing and shearing forces. It is suggested that the jet pump chamber be operated at a Reynolds number above 250,000.

W02008/003996 describes a process for removing oil from particulate matter where an aqueous slurry of the particulate matter is mixed with one or more streams of water which are applied at high pressure, for example 0.5-lOOmpa. By so arranging matters that the mixture then undergoes an adiabatic expansion, the oily material is separated from the particulate matter and can then be collected, further processed if desired, sold, or the like.

While extremely high shear processing in an aqueous medium in which the particulate matter is suspended can serve to separate that particulate matter adequately to provide a commercially useful result, a problem generally arises in connection with the engineering demands placed on the jet pump treatment chamber or the like in which the extreme shear forces are applied.

Downstream of the area of maximum turbulence, the flow of material is still extremely turbulent and this gives rise to major problems in connection with the operating life of the machinery in question. In particular, aqueous slurries containing sand moving at high speed are highly abrasive, and can simply wear through the walls of the chamber and of any downstream pipe leading between the reaction chamber and, for example, a first separating chamber.

According to the present invention there is provided apparatus for treating contaminated particulate mineral material including a mixing chamber, means for introducing contaminated material as an aqueous slurry into the mixing chamber, means for removing the aqueous slurry from the mixing chamber, means for subjecting the slurry, while in the main mixing chamber, to extreme shear forces by injecting water into the mixing chamber at extremely high pressure, and wherein immediately adjacent the injection point the cross section of the chamber transverse to the direction of flow of slurry through it increases substantially, and wherein the walls of the chamber in the area of increased cross section are protected by way of water injected counter-current into the outfiowing agitated slurry stream.

The apparatus of the present invention can be used in a wide variety of applications where it is desired to separate oily material from particulate mineral material. By way of example, one such application is described which is directed to the separation of oil from sand and silt.

It is found that despite efforts to maintain clean processing of crude petroleum, tars, bitumen and the like, into oils and oil based products of greater utility, the products of such refinement are not free of mineral material. When the oil or oil product is stored in storage tanks, because of its higher density, sand and silt containing oily material tends to build up as sludge at the bottom of the storage tanks. This not only reduces the capacity of the storage tanks but also means that periodically the storage tank must be emptied of the desired oil or oil product, the sludge removed and then processed as desired. For environmental reasons it is unacceptable merely to dump such material, and in any event it contains valuable and recoverable quantities ot oil product.

A plant for dealing with such materials is shown diagrammatically, and merely by way of illustrating one way in which the present invention can be put in to practice, is shown in the accompanying drawings in which: Figure 1 is a block diagram showing an overall treatment plant for oily sludge; Figure 2 is a cross section of the reactor vessel forming part of the plant shown in Figure 1; Figure s 3, 4 and 5 show end and side views of the three major components forming the reactor vessel of Figure 2 Figure 6 is a more detailed diagram of the treatment plant, and Figure 7 is a diagrammatic site map of the plant Referring to Figure 1, this shows an integrated plant in block diagram form designed to treat oily sludge, for example as found at the bottom of oil storage tanks. Sludge pumped from the bottom of such tanks is first de-oiled using conventional processes, which can easily extract useful oil therefrom if the oil content is greater than about 40% by weight Thereafter, the concentrated sludge is fed from its source 1 into a slurry tank 2 where it is mixed with water from a holding tank 3. The concentration of oil contaminated solids in the aqueous slurry is chosen to optimise the efficiency of the processing.

The slurry is then pumped to a high pressure reactor chamber 4 described in more detail below. On leaving the high pressure reactor chamber 4, the mixture of particulate mineral material, oily material and water is fed to a separator unit of known type 5 which consists in the example shown of a sand classifier or a set of de-sanding cyclones, both of customary construction. Clean sand is fed from the sand classifier or de-sanding cyclones into a store 6.

The mixture of particulate mineral material, water and oily material is now fed to a de-silter unit 7, of known type. This separates the water, oil and silt into three outputs. The silt is fed to a silt store 8, the oil to a holding tank 9 and the water to a filtration system 10. Filtered water is then fed from filtration system 10 into the water tank 3. Spent filter material is disposed of in customary acceptable fashion by any appropriate means 11.

If desired, the oil product emerging from the de-silter may be subjected to an upgrading process in a conventional upgrading unit 12.

At the heart of the plant shown diagrammatically in Figure 1 is the high pressure reactor chamber 4. Figure 2 shows this in longitudinal section, with the three components from which it is constructed separated for clarity. In practice, they are bolted together to form a sealed unit with an inlet end for slurry 20 and an outlet end 21. The three units are denoted 24, 25 and 26 and Figures 4, Sand 6 show in each case the side and end views of these three components.

The slurry passes upwards as shown in Figure 2. As it passes through component 25, it is violently agitated by water injected under a pressure of e.g. 200 bar, via a ring of eighteen nozzles 27. The nozzles are e.g. 6mm diameter with a total surface area of 108 mm2 and a fan radius of 135 degrees. The agitated flow passes upwards through the lower portion of component 26, with the walls of that component being protected from wear by a rubber liner 31 and by the effect of a counterflow water stream 32 (the main upward flow being in the direction of arrow 33) generated by water injected via an inlet 34 and injected close to the walls by two upwardly directed nozzles 30.

As noted above, the apparatus according to the present invention can be used for a variety of treatment processes. For example, it can be used to process greensand, which is sand encased in bentonite, to remove the bentonite (clay) and reconstitute it. Such used foundry sand can be contaminated with some FAH and phenols. The system can also be used in the removal of Cu, Pb, and As from shooting range sand. As well as the treatment of tank bottoms, the sludge in the bottom of large crude tanks, other applications on refineries may include hydrocatalyst cleaning, silt clean and anaerobic grit cleaning. The plant may also be designed to deal with cleaning oily millscale, and quite generally for processing tar sands and oily sludges.

Claims

CLAIMS1. Apparatus for treating contaminated particulate mineral material including a mixing chamber, means for introducing contaminated material as an aqueous slurry into the mixing chamber, means for removing the aqueous slurry from the mixing chamber, means for subjecting the slurry while in the mixing chamber to extreme shear forces by injecting water into the mixing chamber at extremely high pressure and wherein, immediately adjacent the injection point, the cross-section of the chamber transverse to the direction of flow of slurry through it increases substantially, and wherein the apparatus includes means to inject water into the chamber in the area of increased cross-section counter-current into the outfiowing agitated slurry stream to protect the chamber walls from wear.

C') 15
2. Apparatus according to Claim 1 wherein the water is injected into the mixing chamber via a ring of nozzles.
3. Apparatus according to Claim 1 or 2 wherein the water injected counter-current into the outflowing agitated slurry stream is injected via a pair of nozzles.
4. A method of treating contaminate particulate mineral material to separate the contamination from the particulate material itself which includes the step of passing an aqueous slurry of the contaminated particulate material through apparatus according to any one of the preceding Claims.
5. A method according to Claim 4 wherein the contaminated material is oil contaminated sand or silt.
6. A method according to Claim 4 wherein the contaminated material is oily mill scale.